Scanner using lens array producing inverted images

ABSTRACT

An optically-based and image processing-based scanner including a lens array, an imager, and an array of baffles to define paths of light between the lenses and the imager. Each of the lenses produces an inverted image of a portion of the object to be imaged. Components in the imager transpose and filter the individual images, or vice-versa, and assemble a composite image of the entire object. An array of plano-convex lenses is preferred.

FIELD OF INVENTION

The invention relates to a scanner that uses both optics and imageprocessing to produce a scanned image, and more particularly to ascanner using an array of lenses that produce inverted sub-images forwhich the inverted data thereof is transposed and assembled into acomplete image.

BACKGROUND OF THE INVENTION

Prior art scanners, such as might be used in a stand-alone manner or ina photocopier or facsimile machine, typically scan one line of pixels ofthe object document at a time. Such prior art which utilizes arrays ofimaging lenses typically performs 1:1 imaging, i.e., neither reducing orenlarging, using non-inverted optical images. An example of a lenssystem that produces such 1:1 non-inverted images is an array ofgradient-index (GRIN)lenses. An advantage of using the GRIN-lens arrayis that a 1:1 non-inverted imaged can be produced entirely with optics,i.e., without the need for image processing.

Currently, the highest resolution GRIN lens array-based scanner is300-400 dots per inch (dpi), but a 600 dpi GRIN lens array-based scanneris anticipated to be commercially available soon. The technology for a1200 dpi GRIN lens array-based scanner is not yet, and might not be fora long time, available.

A disadvantage of a GRIN lens array-based scanner is that it has a poordepth of field (DOF), i.e., a DOF less than 0.5 mm. A typical DOF forprior art GRIN lens array-based scanner is 0.2 mm or 0.3 mm.

It is desirable to have a DOF that is greater than 0.5 mm, andpreferably 1.0 mm or better. A smaller DOF produces a scanner that isnot robust. For example, if a piece of paper does not lie completelyflat on the platen of the scanner because it has a crease in it, thenthe typical prior art DOF of 0.2 mm or 0.3 mm causes the imagecorresponding to the crease in the paper to be out of focus.

Having a depth of focus of 0.3 mm or less means that the mechanicalpositioning tolerances of the platen, lens array and optical-energy toelectrical-energy converter must be less than 0.3 mm. This is difficultto manufacture with a low defect rate.

As resolutions increase, the problems of GRIN lens array-based scannerswill increase. For a given GRIN lens array, changing the optical-energyto electrical-energy converter from 600 dpi to 1200 dpi will cut the DOFapproximately in half. Thus, if the DOF was 0.3 mm at 600 dpi, it willbe approximately 1.5 mm at 1200 dpi with the same GRIN lens array.

Prior art scanners that scan one line of a document at a time typicallyhave an imager (for converting the optical image into electric signals)that is the width of the line to be scanned. For a document on 8.5 inchby 11 inch paper that is in the portrait (rather than the landmark)format, the imager needs to be 8.5 inches wide. Such a prior art imageris formed from a sequence of smaller, e.g., 1 inch, imagers, e.g.,charge coupled devices (CCDs), connected end-to-end together.

The joint between two CCDs represents a non-imaging area on the order ofone picture imaging element (pixel) wide. When used with a GRIN lensarray, the non-imaging joints in the composite imager result in lostimage data because the GRIN lens array produces a 1:1 image, a smallportion of which impinges on the joints. Thus, either image informationat the joints is lost or interpolation must be performed on the imagedata derived from the image formed by a GRIN lens array, which is aproblem.

SUMMARY OF THE INVENTION

An objective of the invention is to improve upon the deficiencies of theprior art GRIN lens array-based scanners. In particular, an objective ofthe invention is to provide a scanner having a more robust depth offield (DOF) than the prior art GRIN lens array-based scanners. Also, anobjective of an invention is to provide a scanner that is moreeconomical to produce than the prior art GRIN lens array-based scanners.

These and other objectives of the invention are achieved by providing animaging apparatus comprising: a lens array including a plurality oflenses, each lens in said lens array forming an inverted optical imageof a portion of an object; an imager to convert the plurality ofinverted optical images into image data; and a baffle array including aplurality of parallel light absorbing baffles, each baffle in saidbaffle array forming a light absorbing border between adjacent opticalpaths, said paths lying between said lens array and said imager.

These and other objects of the invention are also fulfilled by providinga method of calibrating an imaging apparatus (the imaging apparatusincluding a lens array, each lens in said lens array forming an invertedoptical image of a portion of an object, an imager including anoptical-energy to electrical-energy converter to convert the pluralityof inverted optical images into a plurality of inverted image data setscorresponding thereto, respectively, each of said inverted data setsbeing a sequence of data having a beginning part, a middle part and anend part, and a controller to filter said sequence so as to discard saidbeginning and end parts and retain said middle part, and a baffle array,each baffle in said baffle array forming a light absorbing borderbetween adjacent optical paths, said paths lying between said lens arrayand said imager), the method comprising: providing a calibration patternof bars alternating between a first color and a contrasting secondcolor, wherein widths of said bars of said calibration pattern are fixedsuch there is a first transition and a second transition in saidcalibration pattern from said first color to said second colorapproximately aligned with a first and second edge, respectively, ofeach lens in said array thereof; determining, at least indirectly basedupon each of said inverted data sets, a first and second indicator ofwhere said first transition and said second transition occur in each ofsaid inverted data sets, respectively; and storing said first and secondindicators for each of said inverted data sets.

These and other objects of the invention are also fulfilled by providinga method of forming an imaging apparatus, the method comprising: forminga lens array including a plurality of lenses, each lens in said lensarray refracting an inverted optical image of a portion of an object;providing an imager to convert the plurality of inverted optical imagesinto image data; forming a baffle array including a plurality ofparallel light absorbing baffles separated by air gaps and one of a topbaffle and a bottom baffle; aligning said lens array to a first end ofsaid baffle array such that each baffle in said baffle array forms alight absorbing border between adjacent optical paths, said paths lyingbetween said lens array and said imager; attaching said lens array tosaid baffle array; and attaching said imager to said baffle array.

The foregoing and other objectives of the present invention will becomemore apparent from the detailed description given hereinafter. However,it should be understood that the detailed description and specificexamples, while indicating preferred embodiments of the invention, aregiven by way of illustration only, since various changes andmodifications within the spirit and scope of the invention will becomeapparent to those skilled in the art from this detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from thedetailed description given hereinbelow and the accompanying drawingswhich are given by way of illustration only, and thus do not limit thepresent invention and wherein:

FIG. 1 is a block diagram of an optics-based and image-processing-basedscanner according to the invention;

FIG. 2 is a diagram of the image inversion caused by the lens array ofthe embodiment of Figure

FIG. 3 is a diagram depicting the image of the calibration patternformed by the lens array of the embodiment of FIG. 1;

FIG. 4 is a second embodiment of the invention that uses differentoptics than the embodiment of FIG. 1;

FIG. 5 is another embodiment that uses an arrangement of scanners thatis different than the embodiment of FIG. 1;

FIG. 6A depicts a point in the construction process of the scanneraccording to the invention;

FIG. 6B depicts a later point in the construction process of the scanneraccording to the invention;

FIG. 7 depicts a cross section of the structure of FIG. 6A depictedalong the line VII—VII prime; and

FIG. 8 is a diagram illustrating the relationship between thecalibration pattern and the pixel locations in a CCD.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 is a block diagram of the optics-based and image-processing-basedscanner 100 according to the invention. The scanner 100 includes anarray of lenses 102, which in this example is formed of plano-convexlenses 104. The array of lenses 102 faces an object document 108 layingagainst an optional platen 106. The array of lenses 102 is arranged withan array of baffles 110. Each baffle includes a first part 112 and asecond optional part 114. The array of baffles 112 separates the arrayof lenses 102 from an imager 116.

The lenses 104 in the array 102 thereof may be any type of refractinglenses such as, e.g., plano-convex lenses, bi-convex lenses, or lenseshaving one convex surface and one concave surface. The surface curvatureof the lens 104 may be either spherical or aspherical. The lenses 104are preferably spherical, plano-convex lenses. The planar surfaces ofthe lenses 104 face the imager 116 while the convex surfaces of thelenses 104 face the platen 106. The figures depict 3 lenses 104 in thearray 102 for simplicity, but any number of lenses can be used.

The imager 116 of FIG. 1 includes an optical-energy to electrical-energyconverter 117, such as one or more charge coupled devices (CCDs), one ormore complimentary metal oxide semiconductor (CMOS) detectors, or one ormore photonics-technology-based detectors. Each converter 117 has aplurality of pixel detectors. FIG. 1 depicts the converter 117 as aplurality of charge coupled devices (CCDs) 118 commensurate in numberwith the number of lenses 104 such that there is one CCD 118 for eachlens 104. The CCDs 118 are connected to an optional but preferred memory120 via signal lines 122. Note that it is not necessary that the numberof CCDs 118 equals the number of lenses 104.

The memory 120 is connected to a controller 124 via a bi-directionalconnection 126. The controller 124 is preferably a microprocessorembodied on an integrated circuit. The controller is also directlyconnected to the CCDs 118 via control lines 128. An output 130 of thecontroller 124 delivers the scanned image data. An optional butpreferred non-volatile memory, such as a electrically erasableprogrammable read-only memory (EEPROM), 121 is connected via abi-directional signal path 127 to the controller 124.

The baffles 112 and optionally but preferably 114 of the array thereof110 form light absorbing borders alongside optical paths between thelenses 104 and the CCDs 118, respectively. The baffles 112 and 114 aremade to be light absorbing to reduce the amount of light reaching theCCD 118 which did not reflect off the corresponding portion of theobject. The material for the baffles should be inherently lightabsorbing and/or coated with a light absorbing substance.

FIG. 2 is a diagram illustrating how each lens 104 in the array thereof102 refracts light from the corresponding portion of an object 200 asdenoted by only two, for simplicity, rays of light 202 and 204. Theimage on the corresponding CCD 118 in the converter 117 is inverted. Theray 202 from the area A (which is above the area B) of the object 200 isimaged on the CCD 118 below the image for the area B. Also, it is notedthat the area AB of the image sensed by the CCD 118 is smaller than,i.e., reduced relative to, the area AB of the object 200 thatcorresponds to the lens 104 through which the rays 202 and 204 travel.

FIG. 3 is a diagram illustrating the relationship between the array 102of lenses 104 and a calibration pattern 300, resulting in the patternedimages on the CCDs 118. The pattern 300 has black portions 302 and whiteportions 304, each of which is equal in width to the width of the lenses104. However, any repeating pattern of alternating, contrasting colorswill suffice so long as transitions between colors in the repeatingpattern approximately coincide or align with the edges of each lens.Knowing the number of transitions that should be completely imaged byeach CCD 118 makes it possible to calibrate the converter 117, as willbe discussed further below.

In FIG. 3, the top lens 104 ₁ is aligned with a white portion 304 ₁ ofthe calibration pattern 300. A black portion 302 ₂ of the calibrationpattern 300 is aligned with the second lens 104 ₂ while a white portion304 ₂ is aligned with the third lens 104 ₃.

Because the array 102 of lenses 104 produce a corresponding plurality ofreduced images, the charge distribution in the CCDs 118 represent acomplete image of the portion of the calibration pattern to which thecorresponding lens 104 is aligned, plus partial images of the portionsof the calibration pattern immediately above and below the calibrationpattern 300 to which the lens is aligned. More particularly, the CCD 118₁ has a beginning part 314 of the charge distribution that representsthe black portion 302 ₂ of the calibration pattern 300, a middle part316 that represents the white portion 304 ₁ of the calibration pattern300 and an end part 318 representing the black portion 302 ₁ of thecalibration pattern 300. Similarly, the charge distribution in the CCD118 ₂ has a beginning part 320 corresponding to the white portion 304 ₂,a middle part 322 corresponding to the black portion 302 ₂, and an endpart 324 corresponding to the white portion 304 ₁. The charges in thebeginning portion 314, the end portion 318 and the middle portion 322represent the color black, while the charges in the middle part 316, thebeginning part 320 and the end part 324 represent the color white.

The end part 318 of the charge distribution in the first CCD 118 ₁represents light such as the ray 306 coming from the black portion 302 ₁of the calibration pattern. The beginning part 320 of the chargedistribution in the CCD 118 ₂ represents light from the white portion304 ₂. Thus, the end part 318 and the beginning part 320 representnoncontiguous areas of the calibration pattern 300.

If a person were to concatenate the image data provided by the CCDs 118,the result would be a distorted representation of the calibrationpattern 300. However, if one can concatenate the middle parts 316, 322,328 etc., then the resultant image would be an accurate representationof the calibration pattern 300. A technique for such filtration isdescribed below.

FIG. 4 is a diagram of an alternative embodiment of the scanneraccording to the invention that differs from the embodiment of FIG. 1 byincluding a second array 400 of lenses 402. In the example of FIG. 4,the lenses 402 are plano-convex lenses. The convex surfaces of thelenses 402 face the convex surfaces of the lenses 104.

The extra array of lenses 400 of FIG. 4 contribute to images in the CCDs118 that have fewer aberrations. However, it is more preferred to useonly the array 102 of lenses 104 because the reduced cost and complexityof manufacture outweighs the relative increase in accuracy contributedby the additional array 400.

FIG. 5 is a diagram of another example embodiment 500 of the scanneraccording to the invention. It is noted that while FIGS. 1-4 are topcross-sectional views, FIG. 5 is a side cross-sectional view. As such,the array of baffles 110 is not depicted in FIG. 5. Rather, a top baffle502 and a bottom baffle 504 are depicted. Again, the baffles 502 and 504are formed of light absorbent material such that they form a lightabsorbing border alongside an optical path between the lens 104 andimagers 506, 508 and 510. Also again, the baffles 502 and 504 helpreduce the amount of unwanted light that reaches the imagers 506, 508and 510.

In FIG. 5, the irradiating light is assumed to be white light. There arethree filters 512, 514 and 516 situated between the lens 104 and theimagers 506, 508 and 510. Each of the imagers 506, 508 and 510 isidentical to the imager 116 of FIG. 1. The filter 512 is a red filter.The filter 514 is a green filter. The filter 516 is a blue filter. Theimagers 506, 508 and 510 image negligibly different areas of the object108. The choice of the filter colors is variable depending upon theparticular application requirements.

The embodiment 500 of the color scanner of FIG. 5 can alternatively beimplemented by the embodiment of FIG. 1 where the object 108 isilluminated by three different colors of light, rather than themonochrome or white light assumed for FIG. 1. Light of a first color,e.g., from a red light emitting diode (LED), would be impinged upon theobject 108 and the reflection thereof imaged by the imager 116. Afterthe brief illumination with red light, the object 108 would beilluminated with a second color of light, e.g., from a green LED, for anequally brief interval and the reflection thereof imaged by the imager116. After the green illumination, the object 108 would be illuminatedby a third color light, e.g., from a blue LED for the same briefinterval and the reflection thereof imaged by the imager 116.

For a color scanner, the embodiment using three colored LEDs ispreferred to the embodiment using three imagers because the multipleimagers in the latter embodiment result in a more expensiveimplementation.

FIG. 6 is a top plan view of the array 110 of baffles 112 and optionally114. The array 110 has a space 600 into which will be fitted at leastone array of lenses such as the array 102. The ends of the space or gap600 can be formed, e.g., by extending the outermost baffles 112 so thatthey join the outermost baffles 114.

FIG. 6B is a top plan view of the embodiment 100 of the scanneraccording to the invention after the array 102 of lenses 104 has beeninserted into the array 110 of baffles 112 and optionally 114, and afterthe imager 116 has been positioned against the end of the array 110 ofbaffles 112 and optionally 114.

FIG. 7 is a cross-section taken along the line VII—VII′ in FIG. 6A. Notethat either the top baffle 502 or the bottom baffle 504 may beintegrally formed with the baffle array 110.

FIG. 8 shows a portion of FIG. 3 in more detail, for the purposes ofexplaining the filtration process. It is noted that the proportions inFIG. 8 have been distorted for the purposes of simplifying the depictionof the pixel locations P_(O), P₁, P₂, . . . P_(J−1), P_(J) . . . P_(K),P_(K+1), . . . P_(N−1), P_(N), within the CCD 118 ₁.

Again, the charge distribution in the CCD 118 ₁ has a beginning part314, a middle part 316 and an end part 318. The beginning part 314stores charge representative of the black color in pixel locationsP_(K+1) through P_(N). The middle part 316 stores charge representativeof the white color in pixel locations P_(J+1) through P_(K). The endpart 318 stores charge representative of the color black in the pixellocations P₀ through P_(J−1). An image 800 is impinged upon the CCD 118₁. The regions A-I of the calibration pattern 300 are also noted in theimage 800 so as to emphasize the inversion caused by the lens 104.

As discussed previously, the reduction in image size by the lens 104makes it necessary to discard the pixels P₀ through P_(J−1) and thepixels P_(K+1) through P_(N) while retaining the pixels P_(J) throughP_(K). The charge distribution changes or transitions from beingrepresentative of the color black to being representative of the colorwhite from pixels P_(J−1) to P_(J). Similarly, the charge distributiontransitions from being representative of the color white to beingrepresentative of the color black from pixel P_(K) to pixel P_(K+1).

During calibration, the controller 124 can shift out the charges in thepixel locations P₀ through P_(N), i.e., the image data for the pixels P₀to P_(N). The controller 124 will sort the image data P₀ through P_(N)to determine the two transition points. These transition points arestored in a EEPROM 121 for the CCD 118. This process is repeated foreach of the CCDs 118 such that the two transitions for each of the CCDs118 is stored in the EEPROM 121. Once the transitions are known, thecontroller 124 can determine the starting pixel P_(J) and the endingpixel P_(K) of the image data to be saved. The image data from pixels P₀to P_(J−1) and P_(K+1) to P_(N) will be discarded. Again, the values forJ and K will have been uniquely determined for each CCD 118.

The operation of FIG. 1 will be now be described. For simplicity, onlytwo example light rays 132 and 134 have been depicted in FIG. 1. Therays 132 and 134 are reflections off the object 108 which pass throughthe platen 106 and are refracted by the lens 104 to produce data in theCCD 118 representing a reduced image. Similar processes occur in theother lenses 104 and CCDs 118. The controller sends control signals tothe CCDs 118 over the control lines 128 which cause the CCDs 118 toshift their data into the memory 120. The data from each CCD 118 must betransposed. This can be done by storing the data from the CCD 118 in thememory 120 according to the order in which it is output and thentransposing that array. Alternatively, the controller can perform atransposition by simply reading the data for each CCD 118 from thememory 120 in the opposite order in which it was stored from the CCD118. The transposition technique that will be preferred depends upon thedetails of the particular application.

If needed, the controller can control the CCDs 118 to output their data120 at the same time. This would, e.g., permit the next row of pixels tobe irradiated and the CCDs 118 to be correspondingly energized while thecontroller transposed the data from the previous line of pixels in thememory 120.

The scanner 116 has been depicted with a memory 120 and a EEPROM 121that are separate from the controller 124. Alternatively, a controllercould be chosen with sufficient memory on the integrated circuit to makeit possible to eliminate the separate structures 120 and 121.

The filtration process (to remove the unwanted parts of each sub-image)has been described as taking place after the transposition process.However, the filtration could be performed before the transposition;this is a matter of design choice that depends upon the details of theparticular application. The advantage of performing the filtrationbefore the transposition is that it results in less data that must betransposed, i.e., a lesser computational load upon the controller 124.

The formation of the embodiment of the scanner according to theinvention will now be described in terms of FIGS. 6A and 6B. First, thearray 110 of baffles 112 and optionally baffles 114 and the bottom 504are formed by a machining or a molding process, e.g., by an injectionmolding process, as depicted in FIG. 6A. Next, the array 102 of lenses104 is inserted into the corresponding gap 600 in the array 110 ofbaffles 112 and optionally 114, as depicted in FIG. 6B. Also, the imager116 is attached to the end of the array 110 of baffles such that theCCDs 118 (not shown in FIG. 6B) in the imager 116 align with the lenses104. It is noted that either the array 102 of lenses 104 can be insertedinto the array 110 of baffles before the imager 116 is attached, orvice-versa.

After the imager 116 and the array 102 of lenses 104 have been puttogether with the array 110 of baffles 112 and optionally 114, the topbaffle 502 is attached. The order of attachment of the top and bottombaffles 502 and 504 might vary depending upon the particularapplication.

A non-limiting example of dimensions for the embodiment 100 of thescanner according to the invention are a distance of 20 mm between theconvex surfaces of the lenses 104 and the object 108, a 1.6 mm thicknessof lenses 104 and a 10 mm distance between the planar surfaces of thelenses 104 and the CCDs 118. A corresponding width of the lenses 104 is2 mm, so that a 2 mm wide portion of an object results in a 1 mm widecorresponding image of that portion on the CCDs 118 in addition topartial images from adjacent portions of the object. A correspondingwidth of the black portions 302 and white portions 304 of thecalibration pattern 300 is 2 mm.

The calibration process preferably takes place once, preferably at thetime that the scanner is manufactured. However, it may be necessary torecalibrate the scanner, depending upon the effects of aging.

A scanner should have a Modulation Transfer Function (MTF) of 50% orgreater for a given line pattern at an appropriate distance from thelens array 102 to the object 108 (20 mm in the above example). As usedherein, MTF is typically measured for the captured image of an industrystandard line pattern of equal width black and white bars with aperiodicity denoted by the number of line pairs per inch (LPI). Atypical line density for a 300 dpi scanner is 70 LPI, for a 600 dpiscanner is 105 LPI and for a 1200 dpi scanner is 140 LPI. The linepattern produces a modulation in the output of the converter 117 with agreater signal corresponding to the image of a white bar (max) and alesser signal corresponding to the image of a black bar (min). Themodulation transfer function (MTF) is defined as MTF=(max−min)/(max+min), and is expressed as a percentage. The invention is expectedto have an MTF of 50% or greater for 600 dpi and 1200 dpi resolutions.

The invention being thus described, it will be obvious that the same maybe varied in many ways. Such variations are not to be regarded as adeparture from the spirit and scope of the invention, and all suchmodifications as would be obvious to one skilled in the art are intendedto be included within the scope of the following claims.

What is claimed is:
 1. An imaging apparatus comprising: a lens arrayincluding a plurality of lenses, each lens in said lens array forming aninverted optical image of a portion of an object; an imager to convertthe plurality of inverted optical images into image data, said imagerincluding an optical-energy to electrical-energy converter, saidconverter producing a set of inverted image data for each lens in saidarray thereof; and a baffle array including a plurality of parallellight absorbing baffles, each baffle in said baffle array forming alight absorbing border between adjacent optical paths, said paths lyingbetween said lens array and said imager; wherein each of said sets ofinverted image data have a beginning part, a middle part and an endpart, the apparatus further comprising a controller to filter said setsof inverted data so as to discard said beginning and end parts andretain said middle parts.
 2. The apparatus of claim 1, the apparatusfurther comprising a memory, wherein said controller is operable tostore a transposition of each of said middle parts of said sets ofinverted image data in said memory so as to produce non-inverted middleparts corresponding to said sets of inverted image data; and saidcontroller further is operable to assemble said non-inverted middleparts into a composite image of said object.
 3. An imaging apparatuscomprising: a lens array including a plurality of lenses, each lens insaid lens array forming an inverted optical image of a portion of anobject; an imager to convert the plurality of inverted optical imagesinto image data, said imager including an optical-energy toelectrical-energy converter, said converter producing a set of invertedimage data for each lens in said array thereof; and a baffle arrayincluding a plurality of parallel light absorbing baffles, each bafflein said baffle array forming a light absorbing border between adjacentoptical paths, said paths lying between said lens array and said imager;a memory and a controller to control said memory to store atransposition of each of said sets of inverted image data from saidconverter in said memory so as to produce a set of non-inverted imagedata corresponding to each set of inverted image data each of said setsof non-inverted image data in said memory having a beginning part, amiddle part and an end part; said controller being operable to filtersaid sets so as to discard said beginning and end parts and retain saidmiddle parts; and said controller being further operable to assemblesaid middle parts into a composite image of said object.
 4. An imagingapparatus comprising: a lens array including a plurality of lenses, eachlens in said lens array forming an inverted optical image of a portionof an object; an imager to convert the plurality of inverted opticalimages into image data; and a baffle array including a plurality ofparallel light absorbing baffles, each baffle in said baffle arrayforming a light absorbing border between adjacent optical paths, saidpaths lying between said lens array and said imager; wherein each lensin said array thereof is a plano-convex lens, the planar surface of saidplano-convex lens being oriented closer to said imager than said convexsurface and the convex surface of said plano-convex lens being orientedcloser to said object than said planar surface.
 5. The apparatus ofclaim 4, wherein said array of plano-convex lenses is a first arraythereof, the apparatus further comprising a second array of plano-convexlens located between said first array of plano-convex lenses and saidobject.
 6. An imaging apparatus comprising: a lens array including aplurality of lenses, each lens in said lens array forming an invertedoptical image of a portion of an object; a first imager to convert theplurality of inverted optical images into image data; a baffle arrayincluding a plurality of parallel light absorbing baffles, each bafflein said baffle array forming a light absorbing border between adjacentoptical paths, said paths lying between said lens array and said imager;a top light absorbing baffle, arranged to cover the top of said bafflearray, to form a light absorbing border above said optical paths betweensaid lenses of said lens array and said imager; and a bottom lightabsorbing baffle, arranged to cover the bottom of said baffle array, toform a light absorbing border below said optical paths between saidlenses of said lens array and said imager.
 7. A method of calibrating animaging apparatus, the imaging apparatus including a lens array, eachlens in said lens array forming an inverted optical image of a portionof an object, an imager including an optical-energy to electrical-energyconverter to convert the plurality of inverted optical images into aplurality of inverted image data sets corresponding thereto,respectively, each of said inverted data sets being a sequence of datahaving a beginning part, a middle part and an end part, and a controllerto filter said sequence so as to discard said beginning and end partsand retain said middle part, and a baffle array, each baffle in saidbaffle array forming a light absorbing border between adjacent opticalpaths, said paths lying between said lens array and said imager, themethod comprising: providing a calibration pattern of bars alternatingbetween a first color and a contrasting second color, wherein widths ofsaid bars of said calibration pattern are fixed such there is a firsttransition and a second transition in said calibration pattern from saidfirst color to said second color approximately aligned with a first andsecond edge, respectively, of each lens in said array thereof;determining, at least indirectly based upon each of said inverted datasets, a first and second indicator of where said first transition andsaid second transition occur in each of said inverted data sets,respectively; and storing said first and second indicators for each ofsaid inverted data sets.
 8. The method of claim 7, further comprising:transposing each inverted image data set to form a correspondingnon-inverted data set; wherein said step of determining determines saidfirst and second indicators by operating directly upon said non-inverteddata sets.
 9. The method claim 7, wherein said step of determiningdetermines said first and second indicators by operating directly uponsaid inverted data sets.
 10. The method of claim 7, wherein said firstcolor is black and said second color is white.
 11. The method of claim7, wherein said calibration pattern is a repeating pattern.
 12. Themethod of claim 11, wherein said bars in said repeating pattern areapproximately half the width of each lens in said array thereof suchthat an adjacent two of said bars are substantially completely imaged byeach lens in said array thereof.
 13. The method of claim 11, whereineach of said bars in said repeating pattern is approximately equal inwidth to the width of said lenses in said array thereof; the methodfurther comprising controlling said imager to image data correspondingto said calibration pattern such that, for each inverted data set ofsaid plurality thereof, said beginning part and said end part are imagedata for said first color and said middle part is image data for saidsecond color.
 14. The method of claim 13, wherein said first and secondindicators assume one of the following relations: each of said firstindicators is indicative of the last datum of said beginning part andeach of said second indicators is indicative of the last datum of saidmiddle part; each of said first indicators is indicative of the firstdatum of said middle part and each of said second indicators isindicative of the first datum of said end part; each of said firstindicators is indicative of the last datum of said beginning part andeach of said second indicators is indicative of the first datum in saidend part; and each of said first indicators is indicative of the firstdatum of said middle part and each of said second indicators isindicative of the last datum in said middle part.